This invention relates to a security warning circuit for a camera operable in response to the drop of the supply voltage (battery weakness) below a predetermined threshold.
A number of electronic cameras with automatic shutter control and shutter speed display circuits have recently been developed. In such cameras it is essential to know whether the battery supply voltage is suitable or not, since pictures can only be properly taken when the supply voltage lies within a specified range. A common method of making such a determination involves a display element, such as a light emitting diode, which glows steadily with suitably charged batteries when a test button is depressed, but which flickers when the batteries are low. This method is disadvantageous, however, in that no warning is given unless the battery test button or switch is closed, and the photographer may thus use the camera and take unsatisfactory pictures without realizing that the batteries are too weak.